Inhibiting corrosion of deep well tubing



1957 o. B. REYNOLDS INHIBITING CORROSION 0F DEEP wmwamc Filed March 18, 1955 INVENTOR.

. f O. B. REYNOLDS BY ATTORNEYS *INHIBITIN G CORRDSION OF DEEP WELL TUBING Orvel B. Reynolds, Bartlesville, kla., assignor to Phillips Petroleum Company, a corporation of Delaware Application March 18, 1955, Serial No. 495,259

.4 Claims. (Cl. 166-1) This invention relates to a method and apparatus for treating well tubing. In one aspect it relates to a method and apparatus for treating well tubing in place in a well.

Corrosion of well tubing in wells producing natural gas is frequently a serious problem. Various methods have been proposed and tried to reduce or to eliminate corrosion, one of the most effective being the treating of the inside of the well tubing periodically with a liquid corrosion inhibitor. At the present time a small quantity of inhibitor liquid is introduced by pumping into the tubing, shutting the well in and allowing the mixture to run down the tubing. The well is then opened and inhibitor mixture and well production flow to the separator tank and in so doing the inhibitor is mixed with water and any other liquid present. any component thereof is soluble in water or other liquid in the tank future usefuless of the recovered inhibitor may be destroyed. This type of tubing treatment requires that the well be shut in for about an hour and a half for a well of average depth, and about $6 to worth of inhibitor, at present prices, is used. From $6 to $10 worth of inhibitor usually represents a relatively small volume and when a small volume of inhibitor liquid is introduced into the tubing some of the liquid merely falls down the tubing and there is no assurance that a complete wall coating job has been obtained.

An object of my invention is to provide a method and apparatus for effectively treating the inner walls of well tubing to reduce or eliminate tubing corrosion.

Another object of my invention is to provide a method and apparatus for treating well tubing in place in a well.

Still another object of my invention is to provide a method and apparatus for treating well tubing in a well whereby unconsumed treating liquid is recovered for reuse in the same or in another well.

Yet another object of my invention is to provide a method and apparatus for such tubing treating in which consumption of treating liquid is reduced to a minimum.

Yet another object of my invention is to provide a simple, inexpensive apparatus for effectively treating Well tubing in place to minimize tubing corrosion.

Still other objects and advantages of my invention will be realized upon reading the following description, which, taken with the attached drawing, forms a part of this specification.

I accomplish these and other objects by providing a well tubing treating assembly comprising, in combination, a production tubing disposed operatively in a deep well, a casing in said well surrounding said tubing, a first conduit communicating with said tubing for outlet of well fluid, a valve adapted to close the well head end of said tubing, a generally vertically disposed pipe on the other side of said valve, the upper end of said pipe being closed, a swab in one of said pipe and said production tubing, said valve and said production tubing being adapted to pass said swab, a first perforate stop means in said pipe to limit upward movement of said If the inhibitor or niited States Patent ice 2 swab, a source of treating liquid, means for transferring treating liquid from said source to said pipe on the side .of said first stop means opposite said production tubing,

a second perforate stop means in said production tubing for limiting downward movement of said swab in said production tubing, and an opening in said production tubing at a level below said second perforate stop means.

In employing the above apparatus for treating a Well, the operation is carried out in a well having a pressure substantially greater than atmospheric pressure by introducing the swab into the upper end of the well tubing to be treated, introducing treating liquid into said well tubing above said swab and pressuring said swab downward in said tubing in said well, releasing the pressure of the treating liquid and forcing said treating liquid and said swab upward in said tubing by said well pressure substantially greater than atmospheric pressure.

In the drawing, Figure 1 illustrates diagrammatically an elevational view, partly in section, of the apparatus of my invention.

Figure 2 illustrated diagrammatically and partly in section one form of a portion of my apparatus.

Figure 3 illustrates diagrammatically an elevational view, in section, of another embodiment of my invention.

Referring now to the drawing and specifically to Figure 1 reference numeral 1%) identifies a well casing disposed in a well. A production tubing 11 is disposed in casing 10 and the lower portion of the tubing is positioned with a packer 12, as shown. This packer 12 is intended to seal the annulus 12a between the tubing 11 and the casing 10 against escape of pressure fluid from the formation 13 to the well head. Perforations 14 are provided in the casing adjacent the formation 13 so that fluid from the formation can flow into the casing. A pipe 35 is attached to the upper portion of the casing, as shown. A valve 36 is provided in pipe 35. A pipe 37 is attached to the upper portion of the well tubing 11 and carries a valve 16 for control of well production. To the upper end of the tubing 11 is attached a valve 15 and to its upper side is attached a lubricator or other pipe 27. The upper end of this lubricator or pipe 27 is adapted to be closed, as by a valve 19. A pipe 43 carrying a valve 2'1) is attached to the lubricator apparatus 27, the vertical pipe of which is identified by reference numeral 18. The pipe 43 is attached to pipe 18 at a point relatively close to valve 15.. A pipe 42 carrying a valve 22 is attached to pipe 18 above the point of attachment of pipe 43. A pipe 41 is also at tached to pipe 13 at any desired position above the point of attachment of pipe 43. Pipe 41 is provided with a check valve 23 and valve 21, as shown. Attached to pipe 41, intermediate valve 21 and check valve 28, is a pipe 32 provided with a valve 39. A pipe 4-7 is attached to pipe 32, as shown. Pipe 47 is provided with a pump 34, and a check valve 33 and a valve 38, as shown. Pipes 41 and 42. are manifolded to pipe 24-, the latter being supplied with a valve intermediate the points of connection of pipes 41 and 42. Pipe 24 leads to a tank 31 provided with a pipe 48 carrying a valve 49. A second pipe 44 is attached to tank 31 and this latter pipe, provided with a valve 4!), is attached to pipe 24 intermediate a valve 29 and the point of connection of pipe 42. As illustrated in Figure 1, reference numeral 26 is a rubber ball, herein termed a swab. This rubber ball or swab element can be made of natural rubber or a synthetic elastomer, the main requirement being that the ball must not be soluble or otherwise acted upon by any liquid or gas with which it comes into contact. The pipe 43 and valve 20 are suificiently large that the ball 26 can be inserted through this .pipe and valve into the pipe 18. Furthermore, the ball 26 is sufficiently large that on movement through tubing 11 it contacts the walls of 3 the tubing in such a manner that liquid can be retained as a slug or column above the ball.

Within pipe 18 just above the positionof ball 26 is provided a ring or other type of perforate bafile 25, such as a screen, to limit upward movement of the ball in the pipe. Under some conditions during operation according to this invention ball 26 passes upward through tubing 11 at a rather rapid rate under the influence of considerable pressure and the baffle 25 should be sufficiently rigid to stop the ball from further upward movement.

Reference numeral 17 identifies a cover plate or other closure means for closing the top of casing 11).

At or near the bottom of tubing 11 is one or more openings 45 while a short distance above these openings is disposed a screen or bafile 46 which can, if desired, be similar to the screen or baflle 25. Baflie 46 is intended to limit the downward movement of ball 26 so that the ball will not reach openings 45.

Figure 2 illustrates the position of ball 26 in tubing 11 at such time that the ball is moving downward or upward while supporting a column or slug of liquid 51. Figure 3 illustrates another embodiment of my invention in which the swab or element which moves up and down tubing 11 is made of a frame 64 having swab members 63, in disc form, or in cup form, as desired. In Figure 3 the swab members 63 are cup shaped. These swab members 63 are, of course, attached by any suitable means to the support 64. immediately above this plug or swab element 65 is a column or slug of liquid 62.

in this operation of the apparatus of my invention for coating a high pressure well tubing, packer 12 is installed, as illustrated, to seal off well production from the upper levels of the casing and to hold the lower end of tubing 11 against horizontal movement. Pipes 35, 37, 43, 18, 41, 42 and the remainder of the apparatus parts, as shown, in this figure are installed. With valve 15 being closed, valve 26 in pipe 43 is opened and ball 26 is inserted therethrough into pipe 18 in the position illustrated in Figure 1. Valve 21) is then closed.

If a swab similar to the cylindrical swab 65 of Figure 3 is used this swab can be inserted under baffle 25 by unbolting pipe 18 from valve 15 and inserting the swab into the bottom end of pipe 18 and then rebolting the pipe to valve 15.

Tank 31 can be a tank permanently installed at the location of the well or if desired, it can be a portable tank or a truck tank so as to be portable in that it can be moved from one location to another. Tank 31 contains a treating liquid such as a suitable corrosion inhibitor which it is desired to use for applying to the inner wall of tubing 11.

When ball 26 has been inserted in pipe 18 in the position illustrated in Figure l a quantity of liquid inhibitor from tank 31 is pumped by pump 3% through pipe 24 with valves 23 and 2% being opened. Valve 22 in pipe 42 is closed. This inhibitor liquid passes from pipe 24 through pipe 41 containing a check valve 28 and with valve 21 being open. Valve 38 in pipe 47 is closed, as is valve 39 in pipe 32 and valve 19 in pipe 18. When the pressure of liquid in pipe 18 reaches approximately well head pressure the valve 15 is opened and upon continued pumping of inhibitor by pump 30 pressure exerted on the upper side of ball 26 forces the ball downward through valves 15 and into tubing 11. One mode of operation involves continued pumping of liquid inhibitor from tank 31 by pump 36 until ball 26 reaches the baffle 46 in the lower portion of tubing 11. Such a condition is determined when outlet pressure of pump 30 rapidly increases above its previous pressure. When the ball 26 reaches baflie 46 valves 21 and 29 are closed and valve 22 in pipe 42 and valve in pipe 44 are opened. When these latter two valves are opened the high bottom hole pressure in the well operates to force ball 26 with the column of liquid inhibitor upward through tubingll.

,4 The inhibitor flows through valve 15 the lower portion of pipe 18 and through pipes 42, 24 and 44 into tank 31 until such time that ball 26 passes through valve 15 and against the underside of the bafile 25. When ball 26 reaches this position valve 15 is closed to prevent the ball from falling toward the tubing. Also valve 22 in pipe 42 and valve 40 in pipe 44 are closed. This terminates one mode of operation for applying liquid inhibitor to the inner wall of tubing 11. When such an operation is complete, if desired, and when tank 31 is maintained on a truck the truck can be moved to another location for treatment of other wells.

Under some conditions it is desirable to pump only a relatively small volume of liquid inhibitor from tank 31 into pipe 18 on the upper side of ball 26 with valve 15, of course, being open. When a desired volume of liquid is so transferred into pipe 18 and tubing 11 valve 23 and 29 in pipe 24 are closed and valves 21 in pipe 41, 38 in pipe 47 are opened and pump 34 pumps air or any other desired gas, such as natural gas, into pipe 18 for forcing ball 26 with its supported column of liquid in hibitor down the tubing. When the ball 26 reaches the baffle 46 outlet pressure of pump 34 increases valves 21 and 38 are closed and pump 34 is turned ofi. In order to allow the ball 26 to move upward with its remaining load of liquid inhibitor valves 21 and 39 are opened to vent the gas or air with the result that well pressure moves the ball upward until the ball reaches baffle 25. When the ball has reached baffie 25 valves 21 and 39 are then closed and this coating operation is then completed.

The operation according to my invention in which the type of swab apparatus illustrated in Figure 3 is used is the same as that described relative to use in the ball 26, the only difference being in the method in inserting the swab into the lower end of pipe 18.

After the coating operation is completed valve 15 is closed and the well then is ready for production of gas upon opening valve 16 and production fluid flows through pipe 17 for passage to storage or gasoline extraction plant or other disposal as desired.

When liquid inhibitor from tank 31 is used to force the ball 26 or swab 65 all the way down the tubing it is preferable to open valve 49 in vent line 43 so as not to form a vacuum within the tank with the concomitant danger of collapse of the tank.

For treating a well tubing in place in a well with the apparatus and method of my invention any satisfactory treating liquid can be used. The type or particular treating liquid used forms no part of my invention since my invention is directed specifically to method and apparatus for applying known liquids to well tubing. There are numerous suitable treating liquids obtainable from supply houses and such can be purchased and used or if desired ingredients can be obtained and mixed at their point of use.

One particular advantage of my invention is that after the inner wall of the tubing 11 is coated and while the ball or cylindrical swab is being forced upward in the tubing the liquid is run back to the original storage tank 31 and in this manner the treating liquid does not become diluted with water or liquid hydrocarbon from the well. In other words the treating liquid does not become contaminated. As mentioned, above if tank 31 is mounted on a truck and after treating one well the truck can be moved to another well and thus to as many other wells as desired for subsequent treating operations.

If my apparatus and methods are used for treating wells of exceedingly high pressure, for example, in distillate wells, under some conditions it may be desirable to produce the well and to operate the well with the annulus between tubing 11 and casing 10 filled with drilling mud or other weighting liquid as a safety measure. According to my invention 1 can treat the inner walls of tubing 11 with corrosion inhibitor without disturbing the mud load in the annulus 12a.

The ball 26 and the discs 63 of Figure 3 can be made of any desirable elastomeric material providing the material is not soluble and is not disintegrated by contacting with the inhibitor liquid. -If the inhibitor is an aqueous liquid ball 26 and a disc 63 can be made of natural rubber or can be made of a synthetic elastomer. If however, these parts come in contact with liquid or vaporous hydrocarbons it is preferable that they be made of an elastomer which is insoluble in hydrocarbon. Many synthetic elastomeric materials insoluble in hydrocarbon are available and an operator can select the type of elastomer which he desires.

The gas which is pumped by pump 34 for forcing the swab down the tubing can be air, if desired, or it can be a gas such as natural gas or it can be an inert gas such as nitrogen. Hydrogen also can be used, if desired. Ordinarily, however, it is preferable to use either air or natural gas.

The method and apparatus of my invention are used usually in the wells in which the well pressure is sufiiciently high to force the ball or other swab with its load of liquid inhibitor up the tubing.

While certain embodiments of the invention have been described for illustrative purposes the invention obviously is not limited thereto.

The term well tubing as used herein is intended to include the actual production tubing and the vertical pipe 18, the latter usually being in alignment with the production tubing.

Iclaim:

l. A method for treating the inner wall of a deep well tubing in a deep well exhibiting a pressure substantially greater than atmospheric pressure, comprising, introducing a swab into the upper portion of the deep well tubing to be treated, introducing treating liquid into said deep well tubing above said swab, pressuring a fiuid into said deep well tubing above said swab in such a manner as to force said swab and said treating liquid downward in said deep well tubing in said Well, releasing the pressure of the presure fluid in said deep well tubing and forcing said presure fluid, said treating liquid and said swab upward in said deep well tubing by said well pressure substantially greater than atmospheric pressure.

2. A method for treating the inner wall of a deep well tubing in a deep well exhibiting a pressure substantially greater than atmospheric pressure, comprising, introducing a swab into the upper portion of the deep well tubing to be treated, pressuring treating liquid into said deep well tubing above said swab in such a manner as to force said swab downward in said deep well tubing for such a distance as desired to treat said deep well tubing, releasing the pressure on said treating liquid and forcing said treating liquid and said swab up said deep well tubing by said well pressure substantially greater than atmospheric pressure.

3. A method for treating the inner wall of a deep well tubing in a deep well exhibiting a pressure substantially greater than atmospheric pressure, comprising, introducing a swab into the upper portion of the deep well tubing to be treated, pressuring suflicient treating liquid into said deep well tubing above said swab as to form a column of treating liquid for wetting the deep well tubing walls to be treated, pressuring a gas into said deep well tubing above said swab in such a manner as to force said swab and said column of treating liquid downward in said deep well tubing for such a distance as desired to treat said deep well tubing, releasing the gas pressure from said deep well tubing and forcing said swab up said deep well tubing by said well pressure substantially greater than atmospheric pressure.

4. The method of claim 1 wherein the treating liquid is a corrosion inhibitor.

References Cited in the file of this patent UNITED STATES PATENTS Re. 23,583 Eilerts Nov. 18, 1952 907,724 Boyle Dec. 29, 1908 1,023,336 Salsbury Apr. 16, 1912 1,746,071 Cotton Feb. 4, 1930 1,758,376 Sawyer May 13, 1930 1,796,338 Moore Mar. 17, 1931 2,203,966 Otis June 11, 1940 2,392,144 Hall Jan. 1, 1946 2,411,044 Landrum et al. Nov. 12, 1946 2,640,029 Blair May 26, 1953 2,654,436 Carlisle et al. Oct. 6, 1953 

1. A METHOD FOR TREATING THE INNER WALL OF A DEEP WELL TUBING IN A DEEP WELL EXHIBITING A PRESSURE SUBSTANTIALLY GREATER THAN ATMOSPHERIC PRESSURE, COMPRISING, INTRODUCING A SWAB INTO THE UPPER PORTION OF THE DEEP WELL TUBING TO BE TREATED INTRODUCING TREATING LIQUID INTO SAID DEEP WELL TUBING ABOVE SAID SWAB, PRESSURING A FLUID INTO SAID DEEP WELL TUBING ABOVE SAID SWAB IN SUCH A MANNER AS TO FORCE SAID SWAB AND SAID TREATING LIQUID DOWNWARD IN SAID DEEP WELL TUBING IN SAID WELL, RELEASING THE PRESSURE OF THE PRESURE FLUID IN SAID DEEP WELL TUBING AND FORCING SAID PRESURE FLUID, SAID TREATING LIQUID AND SAID SWAB UPWARD IN SAID DEEP WELL TUBING BY SAID WELL PRESSURE SUBSTANTIALLY GREATER THAN ATMOSPHERIC PRESSURE. 